/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.sanselan.formats.png;

import org.apache.sanselan.SanselanConstants;

public interface PngConstants extends SanselanConstants
{

	public static final int COMPRESSION_DEFLATE_INFLATE = 0;

	public final static byte[] IHDR_CHUNK_TYPE = new byte[] { 73, 72, 68, 82 };
	public final static byte[] PLTE_CHUNK_TYPE = new byte[] { 80, 76, 84, 69 };
	public final static byte[] IEND_CHUNK_TYPE = new byte[] { 73, 69, 78, 68 };
	public final static byte[] IDAT_CHUNK_TYPE = new byte[] { 73, 68, 65, 84 };
	public final static byte[] iTXt_CHUNK_TYPE = new byte[] { // 
	105, // 
			84, // 
			88, // 
			116, // 
	};
	public final static byte[] tEXt_CHUNK_TYPE = new byte[] { // 
	0x74, //
			0x45, //
			0x58, //
			0x74, //
	};
	public final static byte[] zTXt_CHUNK_TYPE = new byte[] { //
	0x7A, //
			0x54, //
			0x58, //
			0x74, //
	};

	public final static int IEND = PngImageParser.CharsToQuad('I', 'E', 'N',
			'D');
	public final static int IHDR = PngImageParser.CharsToQuad('I', 'H', 'D',
			'R');
	public final static int iCCP = PngImageParser.CharsToQuad('i', 'C', 'C',
			'P');
	public final static int tEXt = PngImageParser.CharsToQuad('t', 'E', 'X',
			't');
	public final static int zTXt = PngImageParser.CharsToQuad('z', 'T', 'X',
			't');
	public final static int pHYs = PngImageParser.CharsToQuad('p', 'H', 'Y',
			's');
	public final static int PLTE = PngImageParser.CharsToQuad('P', 'L', 'T',
			'E');
	public final static int IDAT = PngImageParser.CharsToQuad('I', 'D', 'A',
			'T');
	public final static int tRNS = PngImageParser.CharsToQuad('t', 'R', 'N',
			'S');
	public final static int gAMA = PngImageParser.CharsToQuad('g', 'A', 'M',
			'A');
	public final static int sRGB = PngImageParser.CharsToQuad('s', 'R', 'G',
			'B');

	// XMP chunk type.
	public final static int iTXt = PngImageParser.CharsToQuad('i', 'T', 'X',
			't');

	public static final byte PNG_Signature[] = { (byte) 137, 80, 78, 71, 13,
			10, 26, 10, };

	public static final String PARAM_KEY_PNG_BIT_DEPTH = "PNG_BIT_DEPTH";
	public static final String PARAM_KEY_PNG_FORCE_INDEXED_COLOR = "PNG_FORCE_INDEXED_COLOR";
	public static final String PARAM_KEY_PNG_FORCE_TRUE_COLOR = "PNG_FORCE_TRUE_COLOR";

	// public static final Object PARAM_KEY_PNG_BIT_DEPTH_YES = "YES";
	// public static final Object PARAM_KEY_PNG_BIT_DEPTH_NO = "NO";

	public static final int COLOR_TYPE_GREYSCALE = 0;
	public static final int COLOR_TYPE_TRUE_COLOR = 2;
	public static final int COLOR_TYPE_INDEXED_COLOR = 3;
	public static final int COLOR_TYPE_GREYSCALE_WITH_ALPHA = 4;
	public static final int COLOR_TYPE_TRUE_COLOR_WITH_ALPHA = 6;

	public static final byte COMPRESSION_TYPE_INFLATE_DEFLATE = 0;
	public static final byte FILTER_METHOD_ADAPTIVE = 0;

	public static final byte INTERLACE_METHOD_NONE = 0;
	public static final byte INTERLACE_METHOD_ADAM7 = 1;

	public static final byte FILTER_TYPE_NONE = 0;
	public static final byte FILTER_TYPE_SUB = 1;
	public static final byte FILTER_TYPE_UP = 2;
	public static final byte FILTER_TYPE_AVERAGE = 3;
	public static final byte FILTER_TYPE_PAETH = 4;

	/*
	 * Background colour Solid background colour to be used when presenting the
	 * image if no better option is available. Gamma and chromaticity Gamma
	 * characteristic of the image with respect to the desired output intensity,
	 * and chromaticity characteristics of the RGB values used in the image. ICC
	 * profile Description of the colour space (in the form of an International
	 * Color Consortium (ICC) profile) to which the samples in the image
	 * conform. Image histogram Estimates of how frequently the image uses each
	 * palette entry. Physical pixel dimensions Intended pixel size and aspect
	 * ratio to be used in presenting the PNG image. Significant bits The number
	 * of bits that are significant in the samples. sRGB colour space A
	 * rendering intent (as defined by the International Color Consortium) and
	 * an indication that the image samples conform to this colour space.
	 * Suggested palette A reduced palette that may be used when the display
	 * device is not capable of displaying the full range of colours in the
	 * image. Textual data Textual information (which may be compressed)
	 * associated with the image. Time The time when the PNG image was last
	 * modified. Transparency Alpha information that allows the reference image
	 * to be reconstructed when the alpha channel is not retained in the PNG
	 * image.
	 */

	public final String XMP_KEYWORD = "XML:com.adobe.xmp";

	/**
	 * Parameter key.
	 * 
	 * Only used when writing Png images.
	 * <p>
	 * Valid values: a list of WriteTexts.
	 * <p>
	 */
	public static final String PARAM_KEY_PNG_TEXT_CHUNKS = "PNG_TEXT_CHUNKS";

}